Process for production of lubricating oils



Mgy 12,1936. u. B. BRAY` e-r Al.

PROCESS FOR PRODUCTION 0E LUBRICATIG OILS Filed Feb. 15, 1934 ...SNES

.Nom Gkmh w INNO Paternal May 1&2, 1936 f PROCESS FOR PRODUCTION OF LUBRICATING OILS -Ulric B.'Bray, Palos Verdes Estates, and Claude "E. Swift, Glendale, Calif., assigner-s to Union Oil Company of California, Los Angeles, Calif., l a corporation of California Application February d3, 1934, Serial No. 711,026

1 claims. (c1. 19e-1s) 1 1 This invention relatesto the process' for treating petroleum to produce lubricating oil and is a continuation-impart of our co-pending application Ser. No.,555,017, led Aug. 4th, 1931.

It has been observed by one of `us that many oils containing asphalt and wax are mixtures of hydrocarbons analogous both to hydrocarbons pre'sentdn parain base oils andfthose present in asphalt base oils. It has been observed by one of us, (Ser. No. 466,189), that during the heating of an oil containing asphalt that a reaction is set up whereby the inherent low viscosity temperature susceptibility of the lubricating oil fractions is destroyed.

In order to preserve the inherent characteristics of the lubricating oil components of crude oil containing asphalt which are impaired by distillation methods, we have, in accordance with the process of the above application, caused the separation of the oilV and wax from the asphalt by a method wherein the lubricating oil constituents present in the crude oil are separated from the asphalt present in such a' manner that the oil retains those characteristics which it possessed in the original crude oil. As a means of attaining this, it has been found advisable. to cause the separation of the asphalt from the oil by means of solvents which are capable of dissolving the oil and which do not dissolve the asphalt. Such solvents are alcohol, ether, mixtures of alcohol and ether, acetone, etc;, particularly naphtha, casinghead gasoline and petroleum fractions normally vaporous at ordinary temperature and pressure. We prefer to use as our solvent a petroleum fraction whichmay be obtained by the rectification of natural gasoline. For some purposes a fraction composed of 6.72% ethane, r12.2% propane,- 19.91% iso-butane and 1.17% normal butane is satisfactory.- However,rby using a fraction containing a higher percentage of ethane, it is possible to produce a lubricating oil having a low Conradson carbony value. Such'a solvent has 'a tendency to leave certain heavyoil fractions in the precipitated asphalt which have a tendency to form a high carbon residue. Such a fraction suitable for the production ofalubricating oil having a low Conradson carbon value would con` tain ethane varying in quantities from 40 to 50% by volume.

It is the purpose of this invention to use this type of solvent .to separate the asphalt from the oil, i. e. a solvent composed mainly of ethane and propane. l

In carrying out the extraction of the oil with this light liquid fraction, the solution .is maintained at a pressure suiilcient to maintain the solvent liquid. The extraction of the oil from the petroleum at such pressures to maintain the solvent liquid, results in an asphalt substantially free of oil compound chiefly of bitumen and a solution of oil and wax i-n the liquid petroleum fraction. The oil dissolved in the Vsolvent contains substantially all of the lubricating oil components which are present in the crude oil and in substantially the same form as they exist in the original crude oil and also'themajor portion of the wax present in the crude oil.

One of the deslrablequalities of a lubricating loil is a low Conradson carbon value. According to the U. S. Government Department'of Commerce, Bureau of Mines Technical Paper 323B, page 86, this value throws some light-upon the relative carbon forming properties of an oil. Oils which possess a low value have less tendency to cause carbon deposition in internal combustion motors during use than do oils which possess a' highvalue.

In general, lubricating oils produced by ordinary v Tanne IlV Conradson carbon valwes s A. E Conradson carbon grade values Paraiiln base lubricating oil produced from Pennsylvania crude 4 0 0.80 Asphaltic base lubricating oil produced from California crude ,40 0.25 Oil produced by our process produced from California crude 40 0. l5

Another desirable quality of lubricating oil is a high resistance towards oxidation. In general, oils which oxidize less rapidly are to be p'referred. Lubricating oils produced from parain `base crudes -have less tendency to oxidize than lubricating oils produced by the distillation of asphalt base crudes. It is one of the character-l istics of the oil produced by our process from I asphalt base crudes containing wax that it possesses a low oxidation value.

One of the methods used to determine theoxidation value of an oil is to be found in the Proceedings of theAmerican Society of Testing Materials, vol. `I24, Part 1I of 1924,' page 964, and is sometimes ,known as' the Sligh method.

In Table II there is shown a comparison of the oxidationr values of" a" lubricating oil produced from paraffin base crude, a lubricating oil produced/by ourprocess from asphalt base crudes containing wax, and a lubricating oil produced by-the distillation of asphalt base crude:

TABLE II l y Sligh oxidation 'values Sllgh oxidation value Paramn base lubricating oil produced from Pennsylvania crude Asphaltic base lubricating oil produced by y our process from California crude Asphaltic base lubricating oil produced from California crude 40.0

It'is thus an object of our invention to .pro-

. pressure whereby the oil containing wax and remaining solvent is chilled to a suihciently low temperature to enable-wax to precipitate out of solution which is separated from the oil and solvent, after which the remaining solvent is separated lfrom the oil.

Other objects and features of our invention will be apparent from the following description g of our process taken from the drawing, representing a schematicarrangement of apparatus.

Referring to the drawing, crude oil from which all of the gasoline, kerosene and gas oil have been removed in tank I is withdrawn through valve 2 and sent by means of pump 3 to line 4 where it meets a stream of solvent under pressure, i. e. the mixture of ethane and propane referred to above coming from storage tank I I through valve I2, pump I3 and line I4. The mixture of topped crude and solvent passes into chiller 5 where the mass is cooled by allowing a portion of the solvent to vaporize under reduced pressure through valve 6 into line 1. The vaporized solvent in line 1 is compressed by compressor 8 and sent to condenser 9 where it is liqueiled and passes by means of line I0 to solvent storage tank I I.

The cooled mass of toppedcrude and solvent in chiller 5 passes by means oi' line I5 to agitator I 6 where it is thoroughly mixed, after which'it passes by means of line I1 to decanter I8 where the asphalt settles out. y

The asphalt in decanter I8 is removed through valve I9 and sent by pump 26 through line 2| to heater 22 where the temperature of the mass is raised suiilciently to vaporize all the solvent and moisture present. The heated mass then vpasses by means Iof line 23 into separator 24 where the asphalt separates out and is removed through valve 25 and line 26 to storage tank 21. The mixf ture of-water and solvent vapors passes from separator 24 through line 28 to condenser 29 where the water vapor is condensed. The mixture of water and solvent vapor passes from, condenser 29 to separator 38 where the water is separated out and is removed through valve 3I and line 32.

The solvent vapor in separator 38 passes by means of line 33 jto compressor 3'4 where it is compressed and sent by means of line 33 to condenser 9 where it is liquefied and passes through line `III to storage tank Il.

Th solvent solution of oil in decanter I8 is withdrawn through line 35 and passes into chiller 36 where the temperature of the mass is lowered to a point sufiicient to cause thorough wax precipitation by allowing a portion of the solvent present in chiller .36 to vaporize under reduced pressure through valve 31y into line 38. The

solventivapor in line 38 is compressed by compressor 39'and sent through line 38' to condenser 9 where it is liquefied and passes by means of line I0 to storage tank II.

' The cooled mass in chiller 36 is withdrawn through valve 40 and line 4I whereafter it is sent The sludge in decanter 5I is removed throughl valve 53 and sent by means of 4pump 54 through line 55 to heater 56 where the temperature of the mass is raised suiliciently to vaporize the solvent. 'I'he heated mass then passes by means of line 51 to separator 58 where the sludge separates out and is Withdrawn through valve 59 and line 80.

. 'I'he solvent vaponpasses from separator 58 through line 6I to scrubbing tower 62 where it is contacted with liquid caustic soda introduced through line 63 to remove any acid present, the caustic soda and impuritiesbeing withdrawn via line 65 and valve 64. 'I'he scrubbed solvent passes from tower 62 through valve 66, line 51,' compressor 68, line 61' to condenser 9 where it is liquefied and passesl by means of line ill to storage tank II.

The acid treated' oil dissolved in solvent in decanter 5I passes by means oi line, 52 to clay tower 80 where any remaining sludgeis'removed. The solvent solution of treated oil then passes from tower 89rby means oi line 69 to evaporator 10 where the solvent present is vaporlzed A'with the aid of steam introduced through closed steam coil 14. 'I'he solvent vapor passes from evaporator 19 through valve 1 I into line 12 thence to compressor 'I3 where it is compressed and sent by means of line 12 to condenser 9 where it is liqueed and passes by means of line I-Il to storage tank II. The solvent-free oil'in evaporator 18 is withdrawn through valve 15 and passes through line 16 into 'storage tank 11. Ii. desiredLthis oil may be subjected to extraction with a. selective solvent,l such as liquid sulphur dioxide, for the described in our co-pending application Ser. No. 555,017. p

As illustrativeof'the operation of the process for one type of oil without intending to limit our invention, the following is an example:-l

'I'he topped oil in tank I at a temperature ap- I proximating 200 F. is mixed with solvent and cooled by allowing a portion of the solvent present to vaporize until a temperature of about 120 F. is attained, after which the mixture of residual oil and solvent is mixed in agitator I1. The thoroughly agitated mass passes into decanter I8 where the solvent solution of oil and wax is separated from the undissolved asphalt. This oil dissolved in solvent is chilled suilciently to cause the wax present to precipitate out by allowing a further portion of the solvent present to vaporize under reduced pressure. 'I'he precipitated wax is removed from the solvent solution of oil by such means as cold settling oentrifuging or lter pressing. The oil substantially free of wax and asphalt dissolved in solvent is next treated `with sulphuric acid introduced from tank 45. The result of this treatment is to remove further quantities of undesirable bodies present in the oil which tend to give the iinished product an increased viscosity temperature susceptibility. After treat` ment with the sulphuric acid, the oil is separated from the solvent and may further be reiined by extraction with a selective solvent such as liquid sulphur dioxide.

The foregoing exemplary description is merely illustrative of a preferred mode of carrying out our invention and is not tobe taken as limiting as manyI variations may be made within the scope of the following claims by a person skilled in the art without departing from the spirit thereof. u

We claim:

l. A process for separating asphalt from oils containing the same which comprises commingling said oil with a liquefied normally gaseous hydrocarbon solvent containing propane and approximately 40% ethane to precipitate asphalt, separating the precipitated asphalt from the oil and solvent and separating the solvent from the Oil.

the oil and solvent and separating the solvent from the oil.

3. A process for separating asphalt from oils containing the same which comprises com- Amingling said oil with a liqueed normally gaseous hydrocarbon solvent containing approximately 40% ethane and the remainder largely propane to precipitate asphalt, separating the precipitated asphalt from the oil and solvent and separating the solvent from the oil.

4. A process for the production of lubricating oil from oil containing wax which comprises commingling said oil in a light liqueiled hydrocarbon.

solvent comprising a mixture containing propane and approximately 40% ethane, vaporizing a part of the solvent in one stage and vaporizing another portion in a second stage to chill the oil and precipitate the wax, separating the precipitated Wax from the remaining oil solvent solution and sepa- -rating the remaining solvent from the oil.

5. A process for the production of lubricating oil from oil containing wax which comprises commingling said oil in a light liqueiied hydrocarbon solvent comprising a mixture containing propane and approximately 40% to 50% ethane, Vaporizing a part of the solvent in one stage and vaporizing another portion in a second stage to chill the oilland precipitate the wax, separating the precipitated wax from the remaining oil solvent solution and separating the remaining solvent from the oil.

6. A process for the production of lubricating oil from oil containing asphalt and Wax which comprises commingling said oil in a light liqueed hydrocarbon solvent comprisingI a mixture containing propane and approximately 40% ethane to precipitate asphalt, separating the precipitated asphalt from the oil, wax and solvent and separating the Wax from the oil and solvent.

'7. A process for the production of lubricating oil from oil containing asphalt and wax which v comprises commingling said oil in a light liquefied .hydrocarbon solvent comprising a mixture containing propane and approximately 40% ethaneto precipitate asphalt, separating the precipitated asphalt from the oil, wax and solvent,-

chilling the oil and solvent-to precipitate the wax, separating the precipitated wax from the oil and solvent and separating the solvent from the oil.

. ULRIC B. BRAY.

CLAUDE E. SWIFT. 

